Working with proxy

**sakshi.13agg** · 10-25-2012, 09:11 AM

I want to create a forward proxy .
And the requirement is that whenever browser hits a URL then that request should first go to that proxy, I want to add a header to this request then the modified request should go back to browser through which it will reach the remote server.

I tried to implement this through running a port on which I will read the request coming from browser .But I do not know how will I send the modified request back to the browser.

Please help me out!

**DarrylBurke** · 10-25-2012, 10:43 AM

Moved from Advanced Java

db

**sakshi.13agg** · 10-25-2012, 12:04 PM

I have written the following code:

Java Code:

import java.io.*;
import java.net.*;


public class ProxyApp {

	public static void main(String a[]) throws IOException , Exception
	{
		ServerSocket proxySocket = new ServerSocket(7456);
		System.out.println("Socket created at port number.....7456.");
		

		
		System.out.println("waiting for browser to connect......");
		
		Socket browserSocket	= proxySocket.accept();
		
		System.out.println("request received from browser......");
		
		
		OutputStream browserOutputStream	= browserSocket.getOutputStream();
		InputStream browserInputStream		= browserSocket.getInputStream();
		
		byte[]       b = new byte[1];

		StringBuffer buf = new StringBuffer();
		String       s ;

		for ( ; ; ) {
			int len ;

			len = browserInputStream.read(b, 0, 1);
			if ( len == -1 ) {
				break ;
			}
			s = new String( b );
			buf.append( s );
			if ( b[0] != '\n' ) {
				continue ;
			}
			break ;
		}

		String bufferedData = buf.toString();
		System.out.println("browser requested......"+bufferedData);
		

		int  start, end ;
		
		start = bufferedData.indexOf( ' ' ) + 1;
		while ( bufferedData.charAt(start) == ' ' ) {
			start++ ;
		}
		end   = bufferedData.indexOf( ' ', start );
		String urlString = bufferedData.substring( start, end );

		System.out.println("browser requested..urlString...."+urlString);

		
		 /*******************reading from server********************************/
		URL url = new URL(urlString);
        URLConnection connection = url.openConnection();
        connection.setDoOutput(true);

        OutputStream remoteOutputStream	=  connection.getOutputStream();
        
        System.out.println("sent to remote......"+bufferedData);
        
        remoteOutputStream.write(bufferedData.getBytes());
        remoteOutputStream.flush();
        remoteOutputStream.close();
        
        System.out.println("Data written to remote server...");
        
       
        InputStream remoteInputStream	= connection.getInputStream();

        byte[]       b1 = new byte[1];

		StringBuffer buf1 = new StringBuffer();
		String       s1 ;

		for ( ; ; ) {
			int len ;

			len = remoteInputStream.read(b1, 0, 1);
			if ( len == -1 ) {
				break ;
			}
			s1 = new String( b1 );
			buf1.append( s1 );
			if ( b1[0] != '\n' ) {
				continue ;
			}
			break ;
		}

		String bufferedData1 = buf1.toString();
		 
		System.out.println("Data read from remote server...bufferedData1..."+bufferedData1);
		 
		
		browserOutputStream.write(bufferedData1.getBytes());
		browserOutputStream.flush();
		browserOutputStream.close();
		 
		System.out.println("Data written to browser...");
		 /**********************************************/


		

		System.out.println("**************END********************");
	}
}

But while getting the input stream from url connection I get Socket Exception.
Please tell me what is wrong...